Speed Control Device for Bicycle

ABSTRACT

A speed control device which is adapted to be used in connection with a derailleur type bicycle has one operation mode for up-shifting the speed and another operation mode for down-shifting the speed. The two operation modes can be affected by an operation lever, and with the operation lever being pivoted in a first plane for the up-shifting operation and in a second plane for the down-shifting operation.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a speed control device for a derailleurtype bicycle and, in particular, to a speed control device including anoperation lever that a user can pivot in a first direction to pull acable that controls the derailleur and a second direction to release thecable.

2. Description of the Related Art

U.S. Pat. Nos. 5,213,005, 5,361,645, 5,479,776 and 6,220,111 disclose aspeed control device including one operation lever that user can use toup-shift the speed and another operation lever to down-shift the speed.However, such speed control device has the disadvantage that theoperator could easily operate the wrong lever in a speed changeoperation.

U.S. Pat. No. 5,287,766 shows a speed control device which utilizes anoperation lever for up-shifting and down-shifting the speed. The speedcontrol device is particularly mounted on a straight handlebar typebicycles. In spite of the advantage of speed control device employingone operation lever as discussed in the proceeding, it is believed thatthere is a need for improvement in the field of speed control device andmore specifically in the curved handlebar type bicycles.

The present invention is, therefore, intended to obviate or at leastalleviate the problems encountered in the prior art.

SUMMARY OF THE INVENTION

According to the present invention, a speed control device, which isadapted to be used in connection with a derailleur type bicycle and hasone operation mode for winding the cable that controls the derailleurand another operation mode for releasing the cable, includes a controlassembly including a first toothed member and a second toothed memberborne on a connecting shaft. The first and second toothed members arerotatable together in first and second directions. The control assemblyfurther includes an operation mechanism which includes a user-inputbeing pivoted in a first plane to cause the first and second toothedmembers rotate in the first direction for winding the cable, and in asecond plane to cause the first and second toothed members rotate in thesecond direction for releasing the cable.

Other objects, advantages, and new features of the present inventionwill become apparent from the following detailed description of theinvention when considered in conjunction with the accompanied drawings

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a speed control device in accordancewith the present invention.

FIG. 2 is an exploded perspective view of the speed control device ofFIG. 1.

FIG. 3 is another exploded perspective view of the speed control devicetaken from a different angle than that of FIG. 2.

FIG. 4 is an exploded perspective view of a control assembly embodyingthe present invention.

FIG. 5 is another exploded perspective view of the control assemblytaken from a different angle than that of FIG. 4.

FIG. 6 is a semi-exploded view of a first engaging mechanism of thecontrol assembly embodying the present invention.

FIG. 7 is a semi-exploded view of a second engaging mechanism of thecontrol assembly embodying the present invention.

FIG. 8 is a semi-exploded view of an operation mechanism of the controlassembly embodying the present invention.

FIG. 9 is a cross-sectional view of the speed control device taken along9-9 of FIG. 2.

FIG. 10 is a cross-sectional view of the speed control device takenalong 10-10 of FIG. 3.

FIG. 11 is a cross-sectional view of the speed control device takenalong 11-11 of FIG. 3.

FIG. 12 is a cross-sectional view of the speed control device takenalong 12-12 of FIG. 2.

FIG. 13 is an extended view of FIG. 12 and shows an operation lever ofthe control assembly, and with the operation lever being pivoted in afirst plane.

FIG. 14 is an extended view of FIG. 9 and shows the control assembly ina position corresponding to FIG. 13.

FIG. 15 is an extended view of FIG. 14 and shows the control assemblyaccomplishing one speed change.

FIG. 16 is an extended view of FIG. 15 and shows the operation leverreturned to its home position after accomplishing the speed change.

FIG. 17 is an extended view of FIG. 9 and shows the control assembly ina position corresponding to FIG. 16.

FIG. 18 is an extended view of FIG. 16 and shows the control assemblybeing pivoted to commence another speed change.

FIG. 19 is an extended view of FIG. 17 and shows the control assemblyadapted to effect multiple speed change in one stroke of the operationlever.

FIG. 20 is an extended view of FIG. 11 and shows the operation leverbeing pivoted in a second plane.

FIG. 21 is an extended view of FIG. 9 and shows the control assemblyincluding a first toothed member and a first pawl disengaged from thefirst toothed member after the control assembly is pivoted in the secondplane.

FIG. 22 is a cross-sectional view showing the control assembly includinga second toothed member and a second pawl engaged with the secondtoothed member upon the disengagement of the first pawl from the firsttoothed member.

FIG. 23 is a cross-sectional view showing the first pawl engaged withthe first toothed member and the second pawl disengaged from the secondtoothed member upon return of the operation lever to its home position.

FIG. 24 is a cross-sectional view of the speed control device takenalong 24-24 of FIG. 1.

FIG. 25 is an extended view of FIG. 24 and shows the operation of abrake assembly embodying the present invention.

FIG. 26 is an extended view of FIG. 25 and shows the operation lever ofthe control assembly will not cause a speed change, despite it isdepressed by the brake assembly.

FIG. 27 is a partial, enlarged view of FIG. 24.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring to the drawings, a speed control device in accordance with thepresent invention is adapted to be used in connection with a derailleurtype bicycle. The speed control device includes a housing 1 defining afirst end 101 and a second end 102 opposite to the first end 101, andone of the first 101 and second 102 ends is adapted to connect to thebicycle. The housing 1 includes an opening 11 in which a controlassembly 2 and a brake assembly 3 are pivotally received. The controlassembly 2 is retained in the opening 11 via a plurality of fasteners13, and the fasteners 13 are inserted through a plurality of apertures12 in the housing 11 and engage in a plurality of apertures 211 in afixing member 21 of the control assembly 2. The control assembly 2includes first engaging mechanism 20 and second engaging mechanism 30connected to the fixing member 21.

The first engaging mechanism 20 includes a pivot 23 mounted to thefixing member 21, and the fixing member 21 includes a through hole 213receiving an end of the pivot 23. The first engaging mechanism 20 alsoincludes a first pawl 24 inserted by and moveably mounted betweenproximal 231 and distal 232 ends of the pivot 23 such that the firstpawl 24 is pivotal in a plane transverse to a longitudinal length of theshaft 23, i.e. the length extending from the proximal 231 to the distal232 ends of the pivot 23. The first pawl 24 is biased by an elasticelement 25. Preferably, the elastic element 25 is a torque spring andincludes a plurality of coaxially disposed coiled sections inserted bythe pivot 23 and a first leg 251 extending therefrom and connecting tothe first pawl 24, and a second leg 252 extending therefrom andconnecting to the fixing member 21. Additionally, the coiled sectionshave radial distances being equal to one another.

The second engaging mechanism 30 includes a connecting shaft 31inserting through a compartment 212 which extends through the fixingmember 21 and is parallel to the through hole 213. The connecting shaft31 is supported by a bearing 22. The bearing 22 is disposed in thecompartment 212 and surrounds a first engaging peripheral section 313 ofthe connecting shaft 31. The engaging peripheral section 313 preferablyhas a circular cross-section. The connecting shaft 31 bears a firsttoothed member 32 and a second toothed member 33 on opposite sides ofthe fixing member 21, respectively. Additionally, the connecting shaft31 includes a plurality of second engaging peripheral sections 314 onwhich the first 32 and second 33 toothed members are mounted. Eachsecond engaging peripheral section 314 has a non-circular cross section.Likewise, the first toothed member 32 includes a hole 321 and the secondmember 33 includes a hole 331, respectively, and the holes 321 and 331,which are inserted by the connecting shaft 31, have shapes conforming tothe second engaging peripheral sections 314 where the first 32 andsecond 33 toothed members are mounted. Therefore, the first 31 andsecond 32 toothed members are connected rigidly and prevented fromrotation with respect to a longitudinal axis of the connecting shaft 31.

The first toothed member 32 includes a toothed section 322 formed on itsouter periphery and including a plurality of teeth, in which twoadjacent teeth have an interconnecting edge 3222 extending in onedirection and in which each tooth has a ridge 3221 extending in anotherdirection parallel to the one direction. The second toothed member 33includes a toothed section 332 formed on its outer periphery andincluding a first plurality of teeth 3321 disposed in a plane and asecond plurality of teeth 3322 disposed in another plane, which may beparallel to the plane of the first plurality of teeth 3321.Additionally, two adjacent teeth of the first plurality of teeth 3321have an interconnecting edge 33212 extending in one direction and eachtooth has a ridge 33211 extending in another direction, which has anangled relationship with respect to the direction of the interconnectingedge 33212. Furthermore, two adjacent teeth of the second plurality ofteeth 3322 have an interconnecting edge 33222 extending in one directionand each tooth has a ridge 33221 extending in another direction, whichis parallel to the direction of the interconnecting edge 33222. Further,the second plurality of teeth 3322 are disposed adjacent to the firstpawl 24, and the first pawl 24 is engagable with the interconnectingedge 33222 between any two adjacent teeth. Particularly, when theelastic element 25 is in a “rest” position, the first pawl 24 is engagedin one of the interconnecting edges 33222 by the elastic element 25.Further, the first pawl 24 includes an engaging section 241 protrudingin a plane which may cross the longitudinal length of the pivot 23 andbeing selectively receivable between two adjacent teeth of the secondplurality of teeth 3322. Moreover, the second toothed member 33 isensured to have a proper distance from the fixing member 21 by a spacer315. The spacer 315 is disposed in the compartment 212 and surrounds thefirst engaging peripheral section 313 of the connecting shaft 31.

The connecting shaft 31 also includes a first stop 311 disposed on aproximal end thereof and a second stop 312 disposed on a distal end 317thereof, respectively. The first stop 311 includes two opposing sidesand a plurality of orifices 3111 extending from one side and toward theother side. The connecting shaft 31 further bears a first elastic member34 which includes a proximal end 341 hooking to a resist edge 14 formedin the housing 1 and a distal end 342 engaging in one of the pluralityof orifices 3111. So, if the connecting shaft 31 is rotated in a firstdirection such that the first elastic member 34 is tensioned, releasingthe first elastic member 34 from tension would cause the connectingshaft 31 to rotate in a second direction, which is opposite to the firstdirection. Moreover, the connecting shaft 31 bears a spacer 316 whichincludes a limiting face 3161 and a tube 3162 inserted by the connectingshaft 31, and a cable-receiving member 35 which includes a hole 351inserted by the connecting shaft 31 and being adapted to receive ashifting cable that is adapted to cause speed change upon operation ofthe speed control device. Additionally, the cable-receiving member 35includes a retaining section 352 on which an end of the shifting cableis secured, and a groove 353 formed on its outer periphery and providedfor preventing a length of the shifting cable which is engaged withouter periphery of the cable-receiving member 35 from dislodgingtherefrom.

In addition, the first stop 311 is provided for containing the firstelastic member 34 in the connecting shaft 31.

The control assembly 2 further includes an operation mechanism 40connected to the second engaging mechanism 30. The operation mechanism40 includes a connecting member 41 being pivotal with respect to theconnecting shaft 31 and in a plane which crosses the longitudinal lengthof the connecting shaft 31. The connecting shaft 31 bears a secondelastic member 36 which includes a proximal end 361 hooking to anotherresist edge 14 formed in the housing 1 and a distal end 342 hooking tothe connecting member 41. The connecting member 41 includes two opposingsides spaced from each other, and one of the sides includes a pluralityof orifices 415 that allow the distal end 342 of the second elasticmember 36 to engage in one orifice 415. So, if the connecting member 41is rotated in a first direction such that the second elastic member 36is tensioned, releasing the second elastic member 36 from tension wouldcause the connecting member 41 to rotate in a second direction, which isopposite to the first direction. Additionally, one of the sides of theconnecting member 41 includes a limit section 416 which is adapted toabut the housing 1 such that the connecting member 41 is adapted to bepivoted to an extent until it is stopped by the housing 1. In theembodiment, the limit section 416 includes a first portion 4161extending in a plane of the side and a second portion 4162 extendingfrom the first portion and in a plane which substantially crosses theplane of the first portion 4161. With the second portion 4162, the limitsection 416 would have a substantial area to abut against the housing 1.

Further, the connecting member 41 defines a gap between the opposingsides and in which the first toothed member 32 is adapted to bereceived, and includes a hole 411 extending through the sides andinserted by the connecting shaft 31. Additionally, the gap may receive abushing 413 and a spacer 414. The operation mechanism 40 furtherincludes a catching member 43 which is moveably connected to theconnecting member 41 by a pivot 42, and the pivot 42 extends through anaperture 412 which extends through the sides of the connecting member 41and a first side of the catching member 43. Thus, the catching member 43is pivotal in a plane which crosses a longitudinal length of the axle42. Additionally, the catching member 43 is biased by an elastic element432. The elastic element 432 is a torque spring and includes a first leg4321 abutting against the catching member 43 and a second leg 4322abutting against the spacer 414. Particularly, when the elastic element432 is in a “rest” position, the elastic element 432 keeps the catchingmember 43 away from the first toothed member 32. Moreover, the catchingmember 43 includes a catching section 431 which is formed on its firstside and is selectively engagable with the toothed section 322 of thefirst toothed member 32.

The operation mechanism 40 further includes a second pawl 44 which ismoveably connected to the connecting member 41 by an axle 443, and anoperation lever 45 which is moveably connected to the connecting member41 through the catching member 43. The axle 443 extends through twosecond sides of the catching member 43 which extends from the first sideand are disposed oppositely, and a hole 445 of the second pawl 44 whichextends in its longitudinal length. The operation lever 45 includes twolugs 451 formed on an end thereof and are spaced from each otheroppositely. The second pawl 44 and the operation lever 45 are pivotal ina plane which crosses a longitudinal length of the axle 443. Inaddition, the second pawl 44 includes a first engaging section 441 and asecond engaging section 442 which protrude radially outwardly from anouter periphery thereof, and the first 441 and second 442 engagingsections extend in two different directions. Moreover, the second pawl44 and the operation lever 45 are biased by elastic elements 444 and453, respectively. The elastic element 444 is disposed between theoperation lever 45 and the second pawl 44, and the elastic element 453is disposed between the operation lever 45 and the catching member 43.Preferably, the elastic elements 444 and 453 are torque springs, and theelastic element 444 includes a first leg 4441 abutted against the firstengaging section 441 of the second pawl 44 and a second leg 4442 abuttedagainst a stop wall 452 of the operation lever 45 which extends betweenthe lugs 451, and the elastic element 453 includes a first leg 4531abutted against the catching member 43 and a second leg 4532 abuttedagainst the stop wall 452 of the operation lever 45.

Additionally, the first engaging section 441 of the second pawl 44 isadapted to selectively engage with the first plurality of teeth 3321 ofthe toothed section 332 formed on the second toothed member 33.

Further, the first pawl 24 includes a protrusion which includes a firstsurface 242 being selectively depressible by the second engaging section442 of the second pawl 44 to cause the engaging section 241 of the firstpawl 24 disengage from the second plurality of teeth 3322 of the secondtoothed member 33.

The speed control device has two operation modes. In one operation mode,i.e. the cable-winding operation as shown in FIGS. 10 through 15, theoperation lever 45 is pivoted from its control end 454, but notnecessary, to pivot the catching section 431 of the catching member 43to engage with the first toothed member 32 and then cause rotation ofthe first toothed member 32, and as the first toothed member 32 isrotated the second toothed member 33 is rotated concurrently, then theengaging section 241 of the first pawl 24 is shifted from a beginningposition in which the engaging section 241 is engaged between a pair ofteeth in the first toothed member 32 to a new position in which engagingsection 241 is engaged with the next pair of teeth if one speed changeis to be made, and next the operation lever 45 is returned to its homeposition, i.e. an initial position where the operation lever 45 ispositioned before commencing this cable-winding operation (as shown inFIG. 9). Additionally, FIG. 19 shows that the control assembly 2 isadapted to effect multiple speed change in one stroke of the operationlever 45.

In another operation mode, i.e. the cable-releasing operation, as shownin FIGS. 20 through 23, the operation lever 45 is pivoted in a planewhich crosses that for the cable-winding operation and is then releasedto accomplish the cable-releasing. When the operation lever 45 ispivoted from an initial position where the operation lever 45 ispositioned before commencing this cable-releasing operation, the secondpawl 44 is pivoted in one direction, the first engaging section 441 canengage in the first plurality of teeth 3321 of the toothed section 332formed on the second toothed member 33 and the second engaging section442 of the second pawl 44 can depress the first surface 242 of theprotrusion of the first pawl 24 to disengage the first pawl 24 from thesecond plurality of teeth 3322 of the toothed section 332 formed on thesecond toothed member 33, and the first engaging section 441 of thesecond pawl 44 is engaged in the first plurality of teeth 3321 of thesecond toothed member 33 before the first pawl 24 is disengaged from thecurrent pair of teeth. In this case, the second 33 toothed memberrotates in a direction (as shown in FIG. 22) reverse to a directionoccurred during the cable-winding operation. Additionally, theengagement of the first engaging section 441 in the first plurality ofteeth 3321 of the toothed section 332 formed on the second toothedmember 33 has the function to limit the rotation of the second toothedmember 33, and hence the complete assembly-the connecting shaft 31, thefirst 32 and second 33 toothed members and the cable receiving member35-to a single step.

When the operation lever 45 is released to return to the initialposition where the operation lever 45 is positioned before commencingthis cable-releasing operation, the second pawl 44 is pivoted in anotherdirection, and the second engaging section 442 of the second pawl 44 isdisengaged from the first surface 242 of the protrusion of the firstpawl 24, and as the second engaging section 442 of the second pawl 44 isdisengaged from the first surface 242 of the protrusion of the firstpawl 24 the first engaging section 441 of the second pawl 44 isdisengaged from the first plurality of teeth 3321 of the toothed section332 formed on the second toothed member 33 the second toothed member 33,and the first pawl 24 is engaged with the second plurality of teeth 3322of the toothed section 332 formed on the second toothed member 33afterwards.

In addition, it is an aspect of the present invention that the operationlever 45 will not cause a speed change despite it is depressed by thebrake assembly 3, as shown in FIGS. 24 through 27. The brake assembly 3includes a brake lever 51 pivotally connected to the housing 1, a shiftlock 52 pivotally connected to the brake lever 51 by an axle 511, and anelastic element 53 which is a torque spring and includes a coiledsection inserted by the axle 511 and a first leg 531 abutted against thebrake lever 51 and a second leg 532 abutted against the shift lock 52.The brake lever 51 includes a stop wall 512 and a control end 513 at anend thereof such that the control end 513 can be operated to pivot thebrake lever 51, but not necessary. The shift lock 52 includes a proximalend 521 which is adjacent to the first pawl 24 and is adapted toselectively abut against a second surface 243 of the protrusion of firstpawl 24, and a distal end 522 which is adapted to selectively abutagainst the stop wall 512 of the brake lever 51. Additionally, thesecond surface 243 is a surface on the protrusion which is opposite tothe first surface 242.

Further, it is another aspect of the present invention that the axle 443is pivoted from a first position through an angle to a second positiondespite that the second pawl 44 is restrained by the shift lock 52.Accordingly, the axle 443 has two opposing straight sides, and the hole445 of the second pawl 45 has a cross section in a shape of a “8”, andthe axle 443 has upper right and lower left sections (as shown in FIG.24) engaged with a wall delimiting the hole 445 when the shift lock 52does not abut against the second surface 243 of the protrusion of firstpawl 24, i.e. the first position, and has upper left and lower rightsections (as shown in FIG. 26) engaged with the wall of the hole 445when the shift lock 52 abuts against the second surface 242 of theprotrusion of first pawl 24, i.e. the second position. Therefore, thisallows the speed control device to have a range in which the operationalcontrol lever 45 can rotate without having the cable released as setforth in the aforementioned context that is related to the cable-releaseoperation, since the shift lock 52 abuts against the surface 242

While the specific embodiments have been illustrated and described,numerous modifications come to mind without significantly departing fromthe spirit of invention, and the scope of invention is only limited bythe scope of the accompanying claims.

1. A speed control device is operable between a cable-winding operationmode and a cable-releasing operation mode, comprising: a controlassembly including a first toothed member, and a second toothed memberborne on a connecting shaft, with the first and second toothed membersbeing rotatable together in first and second directions, with thecontrol assembly further including an operation mechanism being pivotedin a first plane to cause the first and second toothed members rotate inthe first direction for the up-shifting the speed, and with theuser-input being pivoted in a second plane to cause the first and secondtoothed members rotate in the second direction for down-shifting thespeed, and wherein the first engaging mechanism includes a first pawlselectively engaged between two adjacent teeth of a second plurality ofteeth formed on the second toothed member; and wherein the operationmechanism includes a catching member selectively engaged between twoadjacent teeth of a toothed section formed on the first toothed member,and a second pawl including a first engaging section selectively engagedbetween two adjacent teeth of a first plurality of teeth of the toothedsection and a second engaging section selectively engaged with the firstpawl to urge the first pawl away from the first toothed member.
 2. Thespeed control device as claimed in claim 1 wherein the first planecrosses the second plane.
 3. The speed control device as claimed inclaim 1 wherein the catching member pivots in one plane and the secondpawl pivots in another plane which crosses the plane of the catchingmember.
 4. The speed control device as claimed in claim 1 wherein theoperation mechanism includes an operation lever, wherein the second pawland the operation lever are biased by first and second elastic elements,respectively, wherein the first elastic element includes a first legabutted against the first engaging section of the second pawl and asecond leg abutted against the operation lever, and wherein the secondelastic element includes a first leg abutted against the catching memberand a second leg abutted against the operation lever.
 5. The speedcontrol device as claimed in claim 1 wherein two adjacent teeth of thefirst plurality of teeth have an interconnecting edge which extends inone direction, and each tooth has a ridge which extends in anotherdirection, and with the direction of the interconnecting edge having anangled relationship with respect to the direction of the ridge, andwherein two adjacent teeth of the second plurality of teeth have aninterconnecting edge which extends in one direction, and each tooth hasa ridge which extends in another direction, and with the direction ofthe interconnecting edge extending parallel to the direction of theridge.
 6. The speed control device as claimed in claim 1 furthercomprising a housing in which the control assembly is pivotallyreceived, wherein the control assembly includes a fixing memberconnected to the housing, wherein the first mechanism includes a pivotmounted to the fixing member, and wherein the first pawl is inserted bythe pivot and connected to the fixing member and is pivotal in a planewhich crosses a longitudinal length of the pivot
 7. The speed controldevice as claimed in claim 6 wherein the first pawl is biased by a thirdelastic element, and wherein the third elastic element includes aplurality of coaxially disposed coiled sections inserted by the pivot,and a first leg extending therefrom and connecting to the first pawl anda second leg extending therefrom and connecting to the fixing member. 8.The speed control device as claimed in claim 6 wherein the connectingshaft of the second engaging mechanism inserts through the fixingmember.
 9. The speed control device as claimed in claim 8 the secondengaging mechanism includes a fourth elastic element including aproximal end hooked to the housing and a distal end, wherein theconnecting shaft includes a first engaging peripheral section on whichthe fixing member is borne and a second engaging peripheral section onwhich the first and second pawls are borne, and wherein the distal endof the fourth elastic element is hooked to the connecting shaft.
 10. Thespeed control device as claimed in claim 9 wherein the first engagingperipheral section has a circular cross-section and the second engagingperipheral section has a non-circular cross section.
 11. The speedcontrol device as claimed in claim 1 wherein the first pawl includes anengaging section selectively engaged between two adjacent teeth of thesecond plurality of teeth and a protrusion including a first surfaceselectively depressed by the second engaging section of the second pawl.12. The speed control device as claimed in claim 11 further comprising abrake assembly pivotally connecting to the housing, and with the brakeassembly including a brake lever pivotally connected to the housing, ashift lock pivotally connected to the brake lever, and a fifth elasticelement, and wherein the brake lever includes a stop wall and the shiftlock includes a proximal end which is adjacent to the first pawl and isadapted to selectively abut against a second surface of the protrusionof first pawl, and a distal end which is adapted to selectively abutagainst the brake lever.
 13. The speed control device as claimed inclaim 1 wherein the second engaging mechanism includes a cable-receivingmember mounted on the connecting shaft, and with the cable-receivingmember being adapted to receive a shifting cable that is utilized toeffect speed change upon operation of the speed control device.
 14. Thespeed control device as claimed in claim 12 wherein the second pawl isconnected to the catching member by an axle, wherein the second pawlincludes a hole through which the axle is inserted, wherein the axle hastwo opposite straight sides and the hole of the second pawl has a crosssection in a shape of a “8”, and wherein the axle has upper right andlower left sections engaged with a wall delimiting the hole when thefirst pawl is remote from the second surface of the protrusion of firstpawl and has upper left and lower right sections engaged with the wallof the hole when the first pawl abuts against the second surface of theprotrusion of first pawl.
 15. The speed control device as claimed inclaim 4 wherein the operation lever is adapted to return to its homeposition in which the operation of the speed control device is not yetcommenced under the effect of the first and second elastic elements.